High precision reflective mirrors are used in numerous optical devices and applications. One existing technique for making precision metal mirrors is to use a substrate of an aluminum alloy, such as that commonly known in the art as aluminum 6061-T6, and to carry out single point diamond turning (SPDT) of a surface on the substrate, which then serves as the reflective surface. Aluminum 6061-T6 is primarily aluminum, with alloy elements of zinc, chromium, iron, magnesium and silicon. The aluminum 6061-T6 alloy is lightweight, is easily machined by SPDT, and has good long-term stability. Accordingly, this alloy is commonly used to produce reflective mirrors for optical devices.